Voltage control system



Oct. 11, 1932. s. HUBBARD VOLTAGE CONTROL SYSTEM Filed July 14, 1928 2 gwuwntoz Patented Oct. 11, 1932 UNITED vSTATES ALBERT S. HUBBARD, OF BETI-IEL, CONNECTICUT, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO GOULD STORAGE BATTERY CORPORATIGN, OF DEPEVJ, NEVJ' YORK, A CORPORA- 'IION OF DELAWARE Application filed July 14,

The invention relates to systems of electrical distribution and has special reference to a system for supplying B or plate current to a radio apparatus.

The invention may be considered a continuat-ion in part of my co-pending application for patent for rectifying apparatus, filed August 12th, 1927, Serial No. 212,548, wherein Ihave disclosed a system and appalo ratus for converting alternating currents into direct currents of widely different voltages.

In the operation of radio apparatus, particularly receivers, it is well known that there is a certain voltage of plate current needed for the operation of the detector tube or tubes, the radio frequency tubes, the low audio frequency amplifying tubes and the high audio frequency amplifying tubes such, forexample, as those of the power type. The exact voltages necessarily vary in accordance with the characteristics of the tubes used, some detector tubes requiring 22 volts, others 45 volts, and the amplifying tubes requir- 25 'ing from a minimum of to 135 or more. These figures are mentioned simply by way of illustration as there are at present many variations therefrom and as in the future there may be still greater variations as yet probably not contemplated.

The principal object of the present invention is to provide means for varying the resistance in the circuits to the plates of the tubes in the various detector and amplifying stages so that the proper voltage will be supplied thereto at all times, the resistance units being intended and adapted to be thrown into or out of the circuits in numerical accordance with the tubes to be operated.

Another object of the invention is to provide a resistance system connected with the maximum voltage supply circuit and adapted to be thrown into or out of the low audio frequency amplifier circuit or the radio frer quency amplifier circuit at will so that the proper volt-age for the number of tubes employed may be obtained with certainty and accuracy.

Another object of the invention is to provide a resistance control system of this type VOLTAGE CONTROL SYSTEM 1928. Serial No. 292,774.

tien and in combination with filter means and by-pass means, all being capable of assembly and arrangement as a complete unit for supplying the necessarily varying or variable volt-ages, the system considered as a whole also having means for taking care of fluctuations in the initial supply line or power .system.

Still another object of the invention is to provide an arrangement of apparatus and circuits by means of which any and all contingencies may be met insofar as different voltage requirements for different number-s of tubes and tubes of different types may be concerned.

To the attainment of the foregoing and other objects and advantages, the invention preferably consists in the system and arrangement of apparatus and circuits to be hereinafter more fully described claimed, and illustrated in the accompanying drawing in which:

The figure is a diagram illustrating the entire arrangement.

It is thought probably advisable, for the sake of clearness, to describe that portion of the system which is common to the present invention and to that embodied in said copenning application especially as the present drawing shows the present invention as employed in association with the direct current supply system embodied in said co-pending application. It should, however, be distinct ly understood that the present invention is not limited to such an association as it is equally capable of use in any conversion system providing different direct currents at differing voltages which would necessarily be appropriate for vacuum tube operation.

Referring to the drawing in detail the numerals 1 and 2 represent the transformers and' in which 3 and 4 are similar primary windings connected in series preferably through a ballast or high temperature coeflicient variable resistance 5 and supplied with energy from a suitable source 6 of alternating current. The secondary windings 7 and 3, preferably similar in number of turns, size of wire and other characteristics, are connected in opposition so that, but for the rectifying means 9 and 10, they would, in effect, neutralize each other so that there would be substantially no voltage across the terminals 11 and 12. The apparatus further includes a rectifier 9 connected across the secondary 7 and a rectifier connected across the secondary 8 so as to oppose corresponding impulses of the current produced in the respective secondaries, a uni-directional pulsating current being therefore obtained between the terminals. This results from the fact that when the current impulse in the secondary 7 is in a direction to pass the rectiiier 9, the current impulse in the secondary 8 in phase with that of the secondary 7 is opposed by the rectifier 10 so that in effect the secondary 7 is short circuited by the rectifier 9 and the current impulse in the secondary 8 opposed by the rectifier 10 and un opposed by the short circuited secondary 7 is free to complete its circuit by way of 13, 14, 9, 11, 19, the load, and 8. On the following half of the wave, the secondary 8 is short circuited by the rectifier 10, and the impulse in the secondary 7, opposed by the rectifier 9, completes its circuit by way of '19, the load, 20, 12, 10, 14, 13 and 7. The current so produced in the work circuit 19 20 will be a uni-directional pulsating current and will be made of both halves of the waves or impulses, there being theoretically no losses.

The term short circuited as above used is relative only and is dependent upon the internal resistance of the rectifying means used. However, the energy lost is negligible and the current in the primary is unaffected by reason of the fact that one of the transformers in series is always either on open circuit or under load. The direct current voltage across the terminals 19 and 20 is relatively fixed and for the transformers and rectifiers used is the maximum direct current voltage obtainable from the system. In order to obtain additional circuits with voltages differing widely from the voltage across the terminals 19 and 20, I may provide switches 17 and 18 connected to the leads 19 and 20 and engageable with selected contacts 21 and 22 respectively connected with taps on the secondaries 7 and 8 so that any desired number of turns in these secondaries may be thr wn into the work circuit. Of course any desired number of taps and in fact any number of switches may be provided.

For radio work it is necessary to smooth the current and I have therefore shown filter circuits comprising an inductance or choke 23 interposed in the lead 19 and shunted by capacitances 24 and 25 having a connection 26 with the lead 20. The choke 23 may actually and conveniently be of the value of 100 l-lenrys. WVhile the exact value of the condensers 24 may be varied it is very convenient that they be respectively 5 and 12 microfarads. The filter circuits include other condensers to be described.

The lead 19 is brought to the high audio frequency amplifier terminal 27 and the lead 20 is brought to the negative terminal 28 common to all of the circuits involved in a radio apparatus. The maximum voltage is of course derived at the terminal 27. In order to obtain the necessary intermediate voltages for the proper operation of a multistage radio apparatus, I provide a system of resistances including units interposed in shunt-circuits and having associated there with switch means for selectively throwing them into or out of operation. This system includes conductors 29 and 30 brought respectively to the low audio frequency amplifier terminal 31 and the radio frequency ampliiier terminal 32. The conductor 29 is connected with a plurality of contacts 33 of switch devices S3, S S S S and S and the conductor 3 connected with other contacts 34 of these switches. The control further includes resistances R, R R R R and R all connected with the lead 19 and with the contacts 35 of the respective switch devices. Connected with the respective contacts 35 are other resistances R, R R R", R and R connected with other contacts 36 of the respective switch devices. Each switch further includes a movable blade or other equivalent element 37 adapted in one position to bridge the contacts 33 and 35 and in the other position to bridge the contacts 34 and 36. Connected across the leads 19 and 20 is a conductor 38 within which is interposed a voltmeter 39 shunted by a rheostat 40. It is intended that the voltmeter be left permanently in. circuit unless it be of the electrostatic type or unless a zero method of measuring the voltage be used.

The filter 1 cans in addition to the choke 23 and condensers 24 and 25, further includes bypass condensers 41, 42, and 43 of suitable capacity connected with the lead 20 and with the leads 19, 29 and 30 respectively by the low amplifier terminal 31, and the resist- 'ances R to R inclusive each have a sutficlent resistance that when added to the resistis obtained through the lead 19 and it is immaterial to the present invention whether the current be derived as the output of the rectifying system shown herein and also embodied in said co-pending application or whether it be derived from some other source as the resistance system performs its function regardless of the source of current. However, the two systems are shown in conjunction and combination inasmuch as it is possible if not probable that in the commercial development of the invention the two would be used in conjunction and built as a complete B current supply unit. On the other hand it is readily conceivable that the resistance system may be constructed as a complete and separate unit adapted for association and employment with some other type of B current supply. By throwing the movable elements of the switches S to o to the left, the number thus thrown depending upon the number of tubes int-he low amplifier stages, the proper number of resistances R to R are thrown into the circuit and will be, of course, in parallel, thus reducing the resistance in direct accordance with the number of tubes, it being obvious and well known that if there be but a single tube in this circuit the resistance must necessarily be higher than if a larger number be used. The actual connection is effected by the simple bridging of the contacts 83 and 35. By throwing the movable members of the proper number of switches, corresponding to the number of tubes in the radio frequency stages, to the right so as to bridge the contacts 34 and 36, the proper number of resistances R to R are thrown into the circuit. When any switch blade or other movable member is thus thrown it is apparent that the corresponding resistance R to R will be in series with the corresponding resistance R to R thus properly reducing the voltage necessary for the successful operation of the radio frequency stages or circuits. A feature of advantage and importance in this switching system is that it is impossible to employ any resistance unit in the circuit supplying current to the low amplifier stages and the radio frequency stages at the same time, there being consequently no possibility of incorrect connection in this respect.

From the foregoing description and a study of the drawing it will be apparent that I have thus provided a very simple resistance system capable of construction as a complete unit and by means of which there may be an accurate and proper adjustment of voltages for supplying plate current to all the tubes in a radio receiving apparatus. W liile the device is primarily intended for such use it is obvious that it is not limited thereto as it is equally capable of employment wherever it is desirable to operate a plurality of different electrical devices requiring different voltages.

While I have shown and described the preferred embodiment of the invention and certain definite apparatus for carrying it out, it should be understood that the disclosure is merely illustrative of the principles involved and that the right is reserved to make all such changes as will not depart from the spirit of the invention or the scope of the claims hereunto appended.

Having thus described the invention, I claim:

1. In an electrical system of distribution, a main circuit of predetermined voltage including feed and return leads, a feed conductor for supplying an intermediate voltage, and a resistor bank comprising a set of contacts connected in series with said intermediate feed conductor, another set of contacts spaced from said first set, a set of resistances corresponding in number to the number of contacts in said sets and permanently connected at one end to said main circuit feed lead and connected at their other ends to the respective contacts of the second set, a plurality of movable switch members adapted individually to bridge corresponding contacts of the first and second named sets, a second intermediate feed conductor, a third set of contacts connected in series with said second named intermediate feed conductor, a fourth set of contacts, and resistances connected at one end with the respective contacts of the last named set and at the other end with the respective corresponding contacts of the second named set, said movable switch members being individually disposable to bridge the corresponding contacts of the third and last named sets.

2. In an electrical system of distribution, a main circuit of predetermined voltage including feed and return leads, a feed conductor for supplying an intermediate voltage, and a resistor bank comprising a set of contacts connected in series with said intermediate feed conductor, another set of contacts spaced from said first set, a set of resistances corresponding in number to the number of contacts in said sets and permanently connected at one end to said main circuit feed lead and connected attheir other ends to the respective contacts of the second set, a plurality of movable switch members adapted individualy to bridge corresponding contacts of thefirst and second named sets, a second intermediate feed conductor, a third set of contacts connected in series with said second named intermediate feed conductor, a fourth set of contacts, resistances connected at one end with the respective contacts of the last named set and at the other end with the respective corresponding contacts of the second named set, said movable switch members being individually disposable to bridge the corresponding contacts of the third and last named sets, all of the corresponding contacts in the respective sets b ing arranged in a line, and said movable switch members being formed as blades pivoted between the contacts of the first and third sets.

3. In an electrical distribution system, a main circuit of predetermined voltage having feed and return leads, intermediate volt age feed conductors, and a resistor bank for controlling the voltage carried by said intermediate feed conductors comprising a plurality of resistances permanently connected with the main feed lead, a second set of re sistances connected at one end with the respective first named resistances, and movable switch means for connecting a selected one of the first named resistances in series with one of the intermediate feed conductors and for throwing a selected one of the first and second named resistances in series with the other intermediate feed conductor.

4. In a system for distributing plate current to the vacuum tubes of a radio apparatus including radio frequency, low audio frequency and high audio frequency amplifiers, a main circuit for giving maximum predetermined voltage for the tubes of the high audio frequency amplifier, branch circuits, resistance units connected with the main circuit, means for connecting one branch circuit to the main circuit through a selected number of said resistance units corresponding to the number of vacuum tubes in the stages of low audio frequency amplification to obtain the proper voltage for operating the same, additional resistance units, and means for connecting the other branch circuit to the main circuit through a selected number of the second named resistance units in series with the first named resistance units, the number corresponding to the number of vacuum tubes in the radio frequency amplifier whereby to obtain the proper voltage for operating the same.

5. In a system for distributing plate current to the vacuum tubes of a radio apparafiers, a main circuit for giving maximum predetermined voltage for the tubes of the high audio frequency amplifier, branch circuits, resistance units connected with the main circuit, means for connecting one branch circuit to the main circuit through a selected number of said resistance units corresponding to the number of Vacuum tubes in the stages of low audio frequency amplification to obtain the proper voltage for operating the same, additional resistance units, means for connecting the other branch circuit to the main circuit through a selected number of the second named resistance units in series with the first named resistance units, the number corresponding to the number of vacuum tubes in the radio frequency amplifier whereby to obtain the proper voltage for operating the same, and an additional branch circuit shunted across the main circuit and havinga variable resistance therein for supplying voltage to the detector stage.

In testimony whereof I aflix my signature.

ALBERT S. HUBBARD. 

